President Barack Obama is being pressed by opponents of the Keystone XL pipeline to tie any approval to measures that would curb climate change, reflecting mounting pressure on the administration to mitigate the project’s impact if it goes forward.

Chesapeake Energy Corp. made $5.5 billion in pretax profits since its founding more than two decades ago. So far, the second-largest U.S. natural-gas producer has paid income taxes on almost none of it.